G protein linked second messengers Flashcards
Master second messengers receptors and their function
What is the function of alpha 1 receptor and G-protein class
- Gq
- Vasoconstriction
What is the function of alpha 2 receptor and class
- Gi
- Vasodilation
What is beta 1 function
Increase heart rate and contractility
Increase renin
What is beta 2 fxn
Vasodilation
Increase insulin
Is the the alpha 1 & 2, beta 1 & 2 receptor sympathetic or parasympathetic
Sympathetic
Do alpha & beta receptor use
A. Ach
B. NE/Epi
C. Histamine
D. Cheese
B
Which receptor decrease heart rate and contractility of atria
M2
John comes to your office due to an urinary incontinent which receptor does the med you prescribe inhibits the incontinent
M3
Norepinephrine is a _________ agonist that affects predominantly ____,___,____ receptors with little include on_____receptors
André ergib
A1,A2,B1
B2
Phenylephrine binds to ____receptors
Alpha 1
Watch for exacerbation of COPD, asthma, and peptic ulcer in susceptible patients what agents
Cholinomimetic agents
Bill comes in with urinary retention what do you give
Bethanechol
Direct agonist
Cholinomimetic agent
Actives bladder smooth Muschel resistent to AChE
Kat comes with a dx of open angle glaucoma a referral from Dr G what med would you recommend
Carbachol
Cholinomimetic
Same as Ach
What is Neostigmine MOA, clinical use
Increase ACh
Indirect agonists (antichoinesterases)
No CNS penetration
Post operative, MG, urinary retention
What is Physostigmine
Freely crosses BBB
Antidote for anticholinergic toxicity
A farmer comes in with diarrhea, urination, mitosis , bronchospasm, low heart rate. What’s his dx? What do you give?
Organophosphate poisoning
Atropine and pralidoxime
Ipratropium and tiotropium is use in asthma. What receptor does it work on?
Muscarinic antagonist
Atropine is a________ agonist or antagonist. Use to treat_______
Muscarinic antagonist
Bradycardia
A 3-year-old child has been admitted to the emergency department having swallowed the contents of 2 bottles of a nasal decongestant. The active ingredient of the medication is a potent, selective α-adrenoceptor agonist drug. Which of the following is a sign of α-receptor activation that may occur in this patient?
(A) Bronchodilation
(B) Cardiac acceleration (tachycardia)
(C) Pupillary dilation (mydriasis)
(D) Renin release from the kidneys
(E) Vasodilation of the blood vessels of the skin
Mydriasis can be caused by contraction of the radial fibers of the iris; these smooth muscle cells have α receptors. All the other listed responses are mediated by β adrenoceptors (Table 6–4). The answer is C.
Mr Green is a 60-year-old man with poorly controlled hypertension of 170/110 mm Hg. He is to receive minoxidil. Minoxidil is a powerful arteriolar vasodilator that does not act on autonomic receptors. Which of the following effects will be observed if no other drugs are used?
(A) Tachycardia and increased cardiac contractility
(B) Tachycardia and decreased cardiac output
(C) Decreased mean arterial pressure and decreased cardiac
contractility
(D) Decreased mean arterial pressure and increased salt and
water excretion by the kidney
(E) No change in mean arterial pressure and decreased car-
diac contractility
Because of the compensatory responses, a drug that directly decreases blood pressure through a decrease in peripheral vascular resistance will cause a reflex increase in sympathetic outflow, an increase in renin release, and a decrease in para- sympathetic outflow. As a result, heart rate and cardiac force will increase. In addition, salt and water retention will occur. The answer is A.
Full activation of the parasympathetic nervous system is likely to produce which of the following effects?
(A) Bronchodilation
(B) Decreased intestinal motility
(C) Increased thermoregulatory sweating
(D) Increased pupillary constrictor tone (miosis)
(E) Increased heart rate (tachycardia)
Parasympathetic discharge causes bronchial and intestinal smooth muscle contraction and bradycardia. Thermoregula- tory (eccrine) sweat glands are innervated by sympathetic cholinergic fibers, not parasympathetic. The answer is D.
A crop duster pilot has been accidentally exposed to a high concentration of a highly toxic agricultural organophosphate insecticide. If untreated, the cause of death from such expo- sure would probably be
(A) Cardiac arrhythmia
(B) Gastrointestinal bleeding
(C) Heart failure
(D) Hypotension
(E) Respiratory failure
Respiratory failure, from neuromuscular paralysis or CNS depression, is the most important cause of acute deaths in cholinesterase inhibitor toxicity. The answer is E.
A 3-year-old child is admitted to the emergency department after taking a drug from her parents’ medicine cabinet. The signs suggest that the drug is an indirect-acting cholinomi- metic with little or no CNS effect and a duration of action of about 2–4 h. Which of the following is the most likely cause of these effects?
(A) Acetylcholine
(B) Bethanechol
(C) Neostigmine
(D) Physostigmine
(E) Pilocarpine
Neostigmine is the prototypical indirect-acting cholinomi- metic; it is a quaternary (charged) substance with poor lipid solubility; its duration of action is about 2–4 h. Physostig- mine is similar but has good lipid solubility and significant CNS effects. The answer is C.
Actions and clinical uses of muscarinic cholinoceptor ago- nists include which one of the following?
(A) Bronchodilation (treatment of asthma)
(B) Miosis (treatment of glaucoma)
(C) Decreased gastrointestinal motility (treatment of
diarrhea)
(D) Decreased neuromuscular transmission and relaxation of
skeletal muscle (during surgical anesthesia)
(E) Increased sweating (treatment of fever)
Muscarinic agonists cause accommodation and cyclospasm, the opposite of paralysis of accommodation (cycloplegia). In acute angle-closure glaucoma and chronic open-angle glaucoma, this may result in a desirable increased outflow of aqueous and decreased intraocular pressure. These agents may cause bronchospasm but have no effect on neuromuscu- lar transmission. They may cause diarrhea and are not used in its treatment. Muscarinic agonists may also cause sweating, but drug-induced sweating is of no value in the treatment of fever. The answer is B.
Activation of α1 -adrenoceptors mediates
Activation of α1 -adrenoceptors mediates smooth muscle contraction, leading to VC, dilation of pupils, and contraction of the bladder sphincter muscle
Phenylephrine and pseudoephedrine cause
α1 -receptor-mediated vasoconstriction and aer used as nasal decongestant
Activation of α2-adrenoceptors inhibits
the release of norepinephrine from sympathetic neurons, decreases the secretion of aqueous humor, and decreases the secretion of insulin.
• Selective α2-adrenoceptor agonists are used to reduce intraocular pressure (apraclonidine and brimonidine), reduce systemic blood pressure (clonidine), produce sedation(dexmedetomidine), and facilitate drug abstinence(clonidine)
Activation of β1-adrenoceptors?
Activation of β1-adrenoceptors produces cardiac stimulation and increases the secretion
of renin, whereas activation of β2-adrenoceptors mediates smooth muscle relaxation.
• The β1-adrenoceptor agonists such as dobutamine are used to increase cardiac output and blood pressure, whereas the β2-adrenoceptor agonists such as albuterol are
employed as bronchodilators in treating asthma.
Differentiation of high-dose epinephrine versus
norepinephrine
???
Differentiation of high-dose epinephrine versus
norepinephrine
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